1. Field of the Invention
The present invention relates to a picture synthesizing apparatus, particularly to a picture synthesizing apparatus preferable for use in an apparatus which changes a viewpoint, converts images obtained by a plurality of image pickup devices disposed in a car to images from a virtual viewpoint, synthesizes the images, provides an image around the car to a driver, and helps the driver to drive the car, for example, at a parking time.
2. Description of the Related Art
As a conventional image display apparatus, an apparatus has been known which changes a viewpoint of an image actually photographed by a camera, converts the image as if the image were photographed from a virtual viewpoint, and displays the image in a monitor as disclosed in “the Principle of virtual Viewpoint Image Synthesis using a Road Surface Model” (the 7th ITS International Conference). Moreover, an apparatus described in Japanese Patent No. 2610146 has been known which superimposes a predicted backward locus corresponding to a steering angle detected by a vehicular steering angle sensor upon an image of a camera mounted in the car.
However, in the conventional image display apparatus, the predicted backward locus is superimposed upon the image converted as if the image were photographed with the virtual viewpoint, and the image is displayed in the monitor. In this case, there is a problem that a distance to a surrounding solid object is wrongly recognized to be longer than an actual distance in the image of the monitor.
This respect will be described with reference to the drawing. In FIG. 30, a distance between an illustrated own car 2401 and another car 2402 seems to be still sufficiently long in a monitor image. In actual, however, as shown in FIG. 31, the car 2401 is considerably close to the other car 2402. This is because the viewpoint is changed to the virtual viewpoint, and thereby objects apart from the ground such as a bumper are projected into a position farther from a camera than an actual position in the converted image.